Linear meter

ABSTRACT

The present invention is directed to a linear meter for producing a linear indication from a rotatable movement and specifically to the type of linear meter including a cylindrical member. The cylindrical member is rotated about a central axis and progressive portions of a helical line on the surface of the cylindrical member present a linear display along a display line which is parallel to the axis of rotation of the cylindrical member. A plurality of individual light transmission means is positioned adjacent to the display line for transmitting the linear display to produce a crisp and clear output indication. Specifically, the individual light transmission means may include vertical light-conducting members separated by baffles and having twisted inner ends so that the inner ends are aligned with the slanted helical line on the cylindrical member. Also, the plurality of individual light transmission means may be small light pipes for transmitting the light energy to produce the output indication. The walls of the inner ends of both types of the light transmission means may include surfaces which absorb light energy so that only light substantially parallel to the light-absorbing surfaces would be passed through the light transmission means. Other aspects of the invention include the use of direct or reflected light to produce the output indication from the helical line on the cylindrical member. Also, the output indication from the linear meter of the present invention may consist of an increasingly larger light or dark area or may consist of a moving dot or line. The invention also includes the use of a photosensitive material located on one surface of the individual light transmission means so that an output signal, in accordance with the output indication, may be produced. Further, the invention includes the use of electroluminescent material electrically controlled by the activation of the photosensitive so as to produce a remote display or a larger display than could be achieved with the light transmission means alone. A further aspect of the invention includes a compact structure wherein means for driving the cylindrical member are located within the cylindrical member and include a d&#39;&#39;Arsonval meter drive.

United States Patent (72] Inventor [54] LINEAR METER 3 Claims, 20 Drawing Figs.

[52] U.S.Cl 116/129,

116/1 16, 11611244, 240/2.1,250/227, 340/380 [51] Int. Cl G091 9/00 [50] Field of Search 116/57,

116, 129,70, 35, l 14, 135, 124.4;240/1 EL, 2.1; 340/324, 380; 40/13033, 106.52; 73/293; 250/211 R,216, 236, 231, 220, 208, 213 A, 227,219; 324/15 D, 151,315/169 TV 156] References Cited UNITED STATES PATENTS 2,561,508 7/1951 Gregorie et a1. 116/116 2,640,144 5/1953 Levy 240/21 2,678,621 5/1954 Proctor, .lr 116/1 16 2,773,239 12/1956 Parker 324/150 2,875,411 2/1959 Lamb 324/151 FOREIGN PATENTS 465,442 5/1937 Great Britain 116/1 24.4

891,431 12/1943 France 116/116 1,234,826 5/1960 France 116/116 1,346,281 11/1963 France 116/116 Primary Examiner-Louis .1. Capozi AttarneySmyth, Roston & Pavitt ABSTRACT: The present invention is directed to a linear meter for producing a linear indication from a rotatable movement and specifically to the type of linear meter including a cylindrical member. The cylindrical member is rotated about a central axis and progressive portions of a helical line on the surface of the cylindrical member present a linear display along a display line which is parallel to the axis of rotation of the cylindrical member. A plurality of individual light transmission means is positioned adjacent to the display line for transmitting the linear display to produce a crisp and clear output indication. Specifically, the individual light transmission means may include vertical light-conducting members separated by baffles and having twisted inner ends so that the inner ends are aligned with the slanted helical line on the cylindrical member. Also, the plurality of individual light transmission means may be small light pipes for transmitting the light energy to produce the output indication. The walls of the inner ends of both types of the light transmission means may include surfaces which absorb light energy so that only light substantially parallel to the light-absorbing surfaces would be passed through the light transmission means. Other aspects of the invention include the use of direct or reflected light to produce the output indication from the helical line on the cylindrical member. Also, the output indication from the linear meter of the present invention may consist of an increasingly larger light or dark area or may consist of a moving clot or line. The invention also includes the use of a photosensitive material located on one surface of the individual light transmission means so that an output signal, in accordance with the output indication, may be produced. Further, the invention includes the use of electroluminescent material electrically controlled by the activation of the photosensitive so as to produce a remote display or a larger display than could be achieved with the light transmission means alone. A further aspect of the invention includes a compact structure wherein means for driving the cylindrical member are located within the cylindrical member and include a dArsonval meter drive.

LINEAR METER The present invention is directed to a linear meter and specifically to a linear meter which produces linear output indication in accordance with a rotational input drive. lt is often desirable to provide such a linear output indication from'a rotational input. For example, a speedometer in an automobile often has a linear output indication from a rotational input drive. Also, any type of an output meter used with a measuring instrument could be arranged to produce a linear output indication. For example, one very common type of meter movement is a dArsonval meter movement which produces a rotational output drive in accordance with an input signal. lt-is often desirable to use this rotational drive to provide the linear output indication so as to produce an output indication which is accurate and easy to read from most any viewing position for a user of the measuring instrument.

It is known that a rotational movement may be converted into a linear movement through the use of a helical line; specifically, a helical line may be provided on a cylindrical member and a rotation of the cylindrical member about a central axis produces an apparent linear movement of progressive portions of the helical line along a display axis, which display axis is parallel to the central axis. The helical line may subdivide the cylindrical surface into two sections; one section of the helix is opaque and the other section of the helix is transparent, so that a constantly increasing linear display of the type found in a thermometer is produced. The helical line may also consist of a thin strip different from remaining portions of the cylindrical surface so as to produce a linear dot or line display which is constant in width and appears to move along the display axis in a linear fashion.

In either of the above situations, the helical line produces a linear display along the display axis. However, the readout edge of the display includes at least one line which is not perpendicular to the display axis but rather forms some angle with the display axis which angle is in accordance with the helical angle of the helix on the surface of the cylindrical member. In order to produce an output indication which includes a perpendicular line, the prior-art systems have included a lens positioned along the display axis. Specifically, a lens which includes a rounded surface has been used by the prior art, which lens produces an optical image which appears perpendicular to the display axis.

Although the image to the viewer appears to be perpendicular to the display axis, the ima e does not accurately indicate the actual rotational positiofi of the cylindrical member because of existing vertical and horizontal parallax. If the image would always be viewed from a position directly in front of the image, the parallax would not be a serious problem, but when the image is viewed from a side or different vertical position the parallax produces an output indication which does not truly represent the actual position of the cylindrical member. Therefore, the prior-art systems which used the helical line as a means of converting a rotatable movement into a linear movement could not produce a linear display with any great accuracy. These prior-art systems, therefore, have been used for measuring and recording instruments which did not require any great accuracy. A serious additional problem with the prior-art systems was the limited vertical view angle, as in reading ,an ordinary thermometer. Beyond this limited view angle, the user would see no image at all.

The present invention provides an output indication whose readout edge is perpendicular to the display axis and which eliminates the problems of parallax and limited view angle and presents a very accurate and sharply defined output indication in accordance with the actual rotational position of the cylindrical member. Specifically, the present invention includes the use of a plurality of individual light transmission means to produce an output indication in accordance with the sequen' tial transmission of light along individual ones of the light transmission means. This sequential transmission of light is controlled by the rotational position of the cylindrical member.

Specifically, one embodiment of the present invention includes baffles disposed between each adjacent pair of the individual light transmission means so as to prevent the transfer of light between the individual light transmission means and only accept the parallel component of the transmitted light. Also, the individual light transmission means may have their inner ends, which are adjacent to the cylindrical member, twisted so as to be aligned with the helical line, leaving the outer ends vertical. The baffle walls at the inner end may also include lightabsorbing properties so as to prevent unwanted light from passing through the light transmission means. The outer portion of light transmission means may have lightreflective walls so as to conduct light easily around turns. Another embodiment of the invention uses a plurality of small light pipes located along the display axis and which light pipes include hollow lightabsorbing walls at the inner ends so as to absorb unwanted light and only pass the parallel light through the light pipes which represent the actual position of the cylindrical member.

The present invention may produce a linearly moving constant width line or dot output indication or may produce an output indication having an increasing area, such as the output indication commonly found with a thermometer. The type of output indication is in accordance with the structure of the helical line in relation to the cylindrical member. In any of the situations described above, the output indication is without parallax and is very accurately in accordance with the actual position of the cylindrical member. in addition, the view angle is very large.

Since the output indication is very accurately in accordance with the actual position of the cylindrical member, the present invention may use the output indication to produce unique results. For example, the invention also includes the use of photosensitive material individually applied to a particular area and each of the individual light transmission means so as to produce a change in electrical characteristics of the photosensitive area in accordance with the reception and transmission of light energy of an individual one of the light transmission means. This change in electrical characteristics of the photosensitive means may be used to produce an output signal to activate a relay or provide a voltage when the linear display reaches a desired location along the display axis. Since each individual light transmission means has its own light-sensitive material, it may be appreciated that the desired signal location may be chosen through the use of one or more movable sliding contact members. Also, the change in the electrical characteristics of the photosensitive means may be used to produce an output signal which output signal is applied to an electroluminescent material so as to provide for a remote light output indication or to provide for a light output indication which has a greater intensity than that produced by the light transmission means alone.

Other aspects of the invention relate to the use of a light source within the cylindrical member, which light source extends along the length of the cylindrical member so that the light energy is directed to the helical line along the entire length of the helical line. Also, the invention includes the use of a helical line having reflective characteristics so that the light energy may be directed toward the reflective helical line from a position outside of the cylindrical member. When the light energy is directed from without the cylindrical member, the driving means for the cylindrical member may be located completely within the cylindrical member, for example, by a dArsonval meter drive located within the cylindrical member.

A clearer understanding of the invention will be had with reference to the following description and drawings, wherein:

FIG. 1 illustrates a first embodiment of the invention including individual light transmission means with twisted inner ends;

FlG. 2 illustrates in more detail the light transmission means of FIG. 1 positioned along a display axis;

FIG. 2a illustrates an individual one of the light transmission means;

FIG. 3a illustrates a cylindrical member subdivided ,by a helical line to produce a thermometer-type output indication;

FIG. 3b illustrates the output indication produced by the linear meter including the cylindrical member of FIG. 30;

FIG. 4a illustrates a cylindrical member including a helical line and which is constructed so as to produce a linearly moving, constant width output indication;

FIG. 4b illustrates the output indication produced by the linear meter including the cylindrical member of FIG. 4a;

FIG. 5 illustrates a second embodiment of the invention including a plurality of light pipes forming the light transmission means;

FIG. 6 illustrates a third embodiment of the invention, including photosensitive material located on the individual light transmission means;

FIG. 7 illustrate in more detail the structure of the individual light transmission means of FIG. 6 showing the location of the photosensitive material;

FIG. 8 illustrates a fourth embodiment of the invention using light energy reflected from the cylindrical member;

FIG. 9a illustrates a cylindrical member which may be used in the embodiment of FIG. 8, so as to produce a linearly moving, constant width line output indication;

FIG. 9b illustrates the output indication produced by a linear meter including the cylindrical member of FIG. 9a;

FIG. 10a illustrates a cylindrical member which may be used in the embodiment of FIG. 8, so as to produce a thermometer-type output indication;

FIG. [b illustrates the output indication produced by a linear meter including the cylindrical member of FIG. Illa;

FIG. 11 illustrates a fifth embodiment of the invention, including photosensitive material and electroluminescent material;

FIG. 12 illustrates an alternative to the embodiment of FIG. 11 using the light pipes of FIG. and including photosensitive material and electroluminescent material;

FIG. 13 illustrates a sixth embodiment of the invention, including a d'Arsonval meter drive located within the cylindrical member; and

FIGS. 14a and 14b illustrate alternative structures for the light transmission means.

In FIG. I a linear meter constructed in accordance with the teachings of the present invention includes an outer housing 10. Included within the housing is a cylindrical member 12 which may be rotated in a direction shown by the arrow 14 by a drive means 16. As an example, the drive means may be a dArsonval meter drive. 7

The cylindrical member 12 includes a helical line 18 which in the example shown in FIG. 1 divides the cylindrical member into a transparent portion 20 and an opaque portion 22. Included within the cylindrical member 12 is a light source 24 which extends the length of the cylindrical member. For example, the light source 24 may be an elongated incandescent light source or may be a fluorescent light source. A reflector member 26 surrounds the light source 24 and has a shiny inner surface. The reflector member 26 includes an open end 28 so that the light energy is directed through the open end and to the cylindrical member 12.

The housing 10 includes a front wall 30 which has an opening 32. The opening 32 is aligned with the opening 28 of the reflector 26. It can be seen, therefore, that the light produced by the light source 24 is directed by the reflector 26 through the opening 28 and toward the opening 32. The portion of the light energy which reaches the opening 32 is in accordance with the position of thecylindrical member 12. Specifically, the cylindrical member 12 passes light energy to the opening 32 in accordance with the position of the transparent portion 20 of the cylindrical member 12. The rotation of the cylindrical member 12, therefore, produces a progressive uncovering of the opening 32 by the transparent portion 20 of the cylindrical member.

It can be seen, therefore, that the opening 32 forms a display area, which display area displays progressive portions of the light from the light source 24 in accordance with the rotational position of the cylindrical member 12. As the cylindrical member 12 rotates, progressive portions of the helical line 18 pass by the opening 32 to uncover the opening 32 and allow the light to pass. As can be been in FIG. 2, the opening 32 has a dark portion 34 and a light portion 36 and the size of -the dark and light portions is in accordance with the position of the helical line 18. As can be seen in FIG. 2, the helical line 18 is at some angle with respect to the opening 32. It is desirable that the output indication be perpendicular to the opening so that the position of the output indication be uniform across its entire width. It can be seen, therefore, that some means must be provided to use the helical line 18 to produce an output indication which is perpendicular to the opening 32.

The prior-art methods of producing a perpendicular output indication used a continuous lens member having a rounded portion which lens member did produce an image which was perpendicular to the opening 32. However, this type of priorart structure suffered greatly from parallax and the position of the output indication depended to a great extent on the position of the viewer. In addition, there was a serious limitation in view angle beyond which the image disappears, as in a thermometer. The present invention provides for a parallaxfree output indication with a perpendicular edge using a plurality of individual light transmission means which light transmission means are separated from each other and which light transmission means prevent the passage of light between each other. In addition, the present invention yields a very large view angle.

Specifically, the light transmission means of FIGS. 1 and 2 are shown as light transmission means 38 which extend from the opening 32, which opening forms the display area, to a second output indication area 40. The light passing through the transparent portion 20 of the cylindrical member 12 is, therefore, transmitted from the display area 32 through the light transmission means 38 to the second output indication area 40. In order to ensure that the output indication is visible to a viewer, the output area is formed from the end portions 40 of the light transmission means 38. The end portions 40 may have means to diffuse the light energy passing through the light transmission means 38 and produce a visible glow at the end portions 40. For example, the end portions 40 may contain a clear solid material such as clear epoxy or glass which may be glazed or sandblasted or ground so as to diffuse the light energy, creating a secondary light source at the output areas 40. Also, reflective particles or even phosphorescent particles may be buried at the end portions 40 so as to produce a secondary light source at the output opening 40.

In the embodiment shown in FIGS. 1, 2 and 2a, the inner ends of the light transmission means 38 are twisted and curved, as shown at positions 42, and the twisted ends are aligned with the helical line 18. This allows the light to enter each light transmission means 38 abruptly with no light spilling into other light transmission means, yielding a sharp, crisp viewing edge. Also, to ensure that the light energy passing to the end portions 40 accurately indicates the position of the helical line 18, baffle members 44 are located between adjacent pairs of the light transmission means 38. Each light transmission means 38 serves as a separate channel for the passage of light energy and the baffle members 44 prevent light energy from passing between the light transmission means 38. The baffle members 44 may include lightreflective surfaces 45 so that most of the light energy is directed to the ends 40. But, in order to ensure that a sharp image is presented at the ends 40, the inner portions of the baffle members 44 may be light absorptive, as shown at positions 46 so that the initial light energy which passes along the baffles 44 must be relatively parallel to the inner surfaces of the baffles. The use of the light-absorptive areas 46 tends to eliminate unwanted light in individual light transmission means from adjacent portions of the display area 32.

In a detail illustration of the light transmission means shown in FIG. 2a, the light transmission means 38 may include baffle members 44 composed of reflective material, which baffles form the outer walls of the individual light transmission means 38. The outer portions of the light transmission means 38, including the ends 40, may be formed by filling the baffles with a clear transparent material 47, such as an epoxy. The inner portions 49 of the light transmission means may be formed by the hollow spaces between the baffles. The inner portions 49 may then be made lightabsorptive by blackening the inner wall areas 46 of the baffles 44, while the outer wall areas 45 of the baffles 44 remain highly reflective. The structure described with reference to FIGS. 1, 2 and 2a, therefore, provides for a very accurate perpendicular transfer of the light energy at the display area 32 without allowing unwanted oblique light to be passed to the ends 40.

In viewing the ends 40, which ends form a continuous output display to a viewer, progressive ones of the ends 40 light up in accordance with the rotation of the cylindrical member 12. If the individual light transmission means is relatively thin, the incremental change for the lighting up of each of the light transmission means is quite small relative to the total length of all the light transmission means. Therefore, the accuracy of the linear meter of the present invention is directly related to the width of the individual light transmission means and the accuracy may be very high since the width may be made very small.

The cylindrical member, shown in FIG. 1, is illustrated in more detail in FIG. 3a. Specifically, the output display from the plurality of light transmission means using the cylindrical member of FIG. 3a is shown in FIG. 3b. The output display includes a light portion 48 and a dark portion 50 separated by a line 52. This line actually moves sequentially in accordance with the individual ones of the light transmission means passing light energy, and the light portion 48, as in a thermometer, increases or decreases in size in accordance with the rotational position of the cylindrical member 12. It is to be appreciated that the transparent and opaque portions 20 and 22 may be reversed so that the light portion 48 and the dark portion 50 are reversed in position to that shown in FIG. 3b.

FIG. 4a illustrates an alternative structure for a cylindrical member which may be used in the embodiment of the inven tion shown in FIG. 1. Specifically, in FIG. 4a, a cylindrical member 54 includes a pair of opaque portions 56 and 58 separated by a thin transparent helical line 60. The output indication appearing at the ends 40 of the light transmission means 38 shown in FIGS. 1 and 2 would be as shown in FIG. 4b. Specifically, the output indication would include dark areas 62 and 64 separated by a light area 66. The width of the light area would depend upon the width of the helical transparent line 60, shown in FIG. 4a. This light area 66, when viewed at ends 40, would sequentially move back and forth in accordance with the rotation of the cylindrical member 54, andappears as shown in FIG. 4b. It is readily apparent that the structure shown in the above-described FIGS. 1 through 4 provides for an accurate linear output display which does not have parallax, provides a precise indication of the rotational position of a cylindrical member and may be viewed over a very wide angle.

FIG. 5 illustrates a second embodiment of the invention, including a plurality oflight pipes constituting the light transmission means. In FIG. 5, a housing 70 encloses a cylindrical member 72 which may be of the type shown in either FIG. 3a or FIG. 4a. The cylindrical member 72 is rotated by a drive means 74 such as a dArsonval meter drive. Included within the cylindrical member 72 is an elongated light source 76 sur rounded by a reflector member 78, both of which may be similar to the corresponding elements shown in FIG. 1. An opening 80 from the reflector member 78 allows the light to pass from the reflector member and toward an opening 82 in the front portion 84 of the housing 70. The light which passes to the opening 82 is in accordance with the rotational position of the cylindrical member 72. This above-described structure is essentially similar to the corresponding elements shown in FIGS. 1 and 2.

The opening 82 provides for a display area and the light energy at the opening 82 is transmitted by a plurality of light pipes 86. These light pipes 86 may be constructed of a plastic material, such as lucite, or may be constructed of glass. The ends 88 of the light pipes 86 are roughened by sandblasting or glazing so as to diffuse the light energy passing through the light pipes 86 and thereby produce a secondary light source at the ends 88. The inner ends of the light pipes 86 may be constructed of hollow members 90 which include light-absorbent inner surfaces. These hollow members 90 prevent the passage of unwanted light from adjacent portions along the opening 82.

The light passed by the light pipes 86 is therefore accurately in accordance with the position of the helical line on the cylindrical member 72. Since the light pipes 86 are relatively Small, as soon as the helical line passes to a position so as to allow a substantial amount of light energy to be transmitted to an intlividual one of the light pipes, that light pipe produces an output indication at the end 88. The ends of the light pipes 88 therefore are lit in progression in accordance with the position of the cylindrical member 72, and this output indication appears either as a plurality of dots or as a moving dot or pair of dots in accordance with the structure of the cylindrical member 72. It is to be appreciated that each of the individual light transmission means 38 of FIGS. 1, 2 and 2a may be formed by a plurality of light pipes such as light pipes 86 shown in FIG. 5.

FIG. 6 illustrates a third embodiment of the invention, including an outer housing which has a front face 102. The front face 102 includes an opening 104, which opening serves as a display area. A rotating cylindrical member 106, rotated by drive means 107, is enclosed within the housing 100 and the cylindrical member 106 may be of the type shown in either FIG. 3a or FIG. 4a. A light source 108 plus a reflector member 110 directs light energy through an opening 112 toward the opening 104 in the front wall member 102. This abovedescribed structure is essentially similar to that shown in FIG. 1.

A plurality of light transmission means 114 having twisted inner ends 116 parallel to a helical line. 117 and separated by bafi'le members 118 is supported along the opening 104 so as to receive the light energy passing through the opening 112. The light energy passing to the light transmission means is in accordance with the rotational position of the cylindrical member 106.

In FIG. 7, the outer ends 122 ofthe light transmission means 114 are shown in greater detail. In FIG. 7, the light transmission means 114 include outer end faces 120, which outer end faces include roughened portions 122 to provide a visible output indication and include photosensitive material 124 to produce output signals 126. It can be seen that the upper portions 122 of the ends are roughened by sandblasting or glazing so that a visible output indication is produced in the same manner as with reference to the embodiments of FIGS. 1 and 5. In addition, the lower portions 8+. the ends 120 contain individual strips of photosensitive material 124. These strips of photosensitive material 124 are insulated from each other, but at the upper position all of the strips 124 are connected in common to a source of positive voltage, referred to as 8+. At the lower end the strips of photosensitive material 124 are connected to individual output terminals 126. In addition, a plurality of individual resistors 128 are connected between the output terminals 126 and a reference potential such as ground.

It can be seen, therefore, that when light energy is directed to an individual one of the light transmission means, a particular one of the photosensitive strips 124 is activated, thereby changing its electrical characteristics. Specifically, in the example shown in FIGS. 6 and 7, the photosensitive material 124 may be photoresistive material and the resistance of the photoresistive material changes upon the reception of light. For

example, the resistance of the photoresistive material may decrease drastically upon the reception of light energy so that an output signal is developed across an individual one of the resistors 128. 1

If a cylindrical member of the type shown in FIG. 3a is used in the embodiment of FIG. 6, output signals would develop progressively as the ends 122 are lit up in a progressive fashion. If, however, a cylindrical member of the type shown in FIG. 4a is used in the embodiment of FIG. 6, the output signal progresses sequentially as the individual ones of the photosensitive strips are activated. In either situation described above, an output signal may be developed in accordance with the rotational position of the cylindrical member, and this output signal is very accurately in accordance with the rotational position of the cylindrical member.

As a particular example, it may be desired to provide for a warning in accordance with a predetermined output indication of the linear meter of the present invention. A particular output terminal 126 is chosen in accordance with the predetermined output indication and this output terminal may be connected to a warning device (not shown). When the cylindrical member 106 is rotated the appropriate distance to provide the predetermined output indication, the particular one of the light transmission means is activated. Light then passes down the particular one of the light transmission means and the strip of photosensitive material 124 is activated to produce an output signal across a particular one of the resistors 128 at the particular output terminal connected to the warning device. It is also obvious that the structure shown in FIG. 6 may be used to provide for automatic control by connecting control equipment to particular ones of the output terminals 126. The control equipment would then be activated in accordance with the production of output signals at the particular ones ofthe output terminals 126.

In the prior art, the light source and photosensitive material are one or both physically moved, depending at what position it is desired to achieve an output signal. In the present invention, the light source and photosensitive material are both fixed and the user may either attach to one or a combination of terminals 124, at which signal outputs are desired. In addition, the baffles help give crisp positive action.

FIG. 8 illustrates yet another embodiment of the invention using light reflected from the cylindrical member rather than light passing through the cylindrical member as shown in the prior figures. In FIG. 8, an outer housing 150 contains a cylindrical member 152. The cylindrical member 152 may be rotated by a drive means 154. The cylindrical member 152 may be either of the type shown in FIGS. 9a and a. Specifically, in FIG. 9a the cylindrical member includes a pair of light-absorbing surfaces 156 and 158 separated by a helical strip of light reflective material 160.

In FIG. 10a the cylindrical member includes a first lightreflective surface 162 and a second light-absorbing surface 164 separated by a helical line 166. It is to be appreciated that the output indication using the cylindrical member shown in the FIGS. 9a and 10a would be of the type shown in FIGS. 9b and 10b. Specifically, in FIG. 9b the output indication would be a pair of dark areas 168 and 170 separated by a light area 172, which light area moves back and forth in accordance with the rotation of the cylindrical member shown in FIG. 9a. In FIG. 10b the output indication includes a light area 174 and a dark area 176 separated by a line 178, which line moves back and forth so that the light area is increased or decreased in accordance with the rotation of the cylindrical member shown in FIG. 10a.

In FIG. 8, the cylindrical member 152 is shown to be of the type illustrated in FIG. 10a and includes a light-reflective surface 162. The light is directed to the reflective surface 162 from a pair of light sources 180 and 182, which light sources pass light energy to a pair of light-transmitting members 184 and 186. The light-transmitting members 184 and 186 include highly reflective surfaces 188 and 190 so that the light energy from the light sources and l82is transmitted along the members 184 and 186 in the direction shown by the arrows 192 and 194.

The light energy, as shown by the arrows 192 and 194, strikes the reflective surface 162 which directs the reflective light energy to a plurality of individual light transmission means 196. The individual light transmission means 196 is similar to those shown in FIG. 1. Specifically, the individual light transmission means 196 includes baffle members 198 defining the outer walls of the light transmission means. These baffle members 198 are highly reflective at the outer end and are light-absorbing at the inner end.

FIG. 11 illustrates another embodiment of the invention, including an outer housing 250 which contains a cylindrical member 252. The cylindrical member 252 may be of the type shown in either FIGS. 3a or 40. A drive means 254 provides for rotation of the cylindrical member 252. A light source is provided by a light pipe 256 and a source of light energy, such as an incandescent light source 258. It can be seen that when the incandescent light source 258 is energized, light energy is directed down the light pipe 256. The light pipe includes a clear end portion 260 which end portion extends the length of the helix and is shaped to direct light toward an opening 262 in a front wall member 264. A plurality of individual light transmission means 266 similar to those shown in FIG. 1 is used to transmit the light energy from the opening 262.

The outer ends of the individual light transmission means 266 are covered with individual strips of photosensitive material 268 which photosensitive material may be, for example, photoresistive material. The individual strips of photosen sitive material 268 are insulated from each other, but at one end all of the strips of photosensitive material 268 are connected to each other and to a source of AC or DC voltage marked Brl. The other ends of the strips of photosensitive material 268 are connected to individual ones of strips of electroluminescent material 270. The ends of the strips of electroluminescent material 270 remote from the connection to the photosensitive material 268 are connected to a reference potential such as ground.

The electroluminescent material emits light upon the passage of current through the electroluminescent material. As individual ones of the strips of photosensitive material 268 are energized in accordance with the reception of light energy which in turn is controlled by the position of the cylindrical member 252, the resistance of the individual ones of the strips of photosensitive material decreases, thereby providing for an increased current flow through particular ones of the strips of electroluminescent material 270. The individual ones of the strips of electroluminescent material 270 thereby light up to provide for an output indication in accordance with the position of the cylindrical member 252. It is to be appreciated that the strips of electroluminescent material may be located at a remote position so that the output indication of the linear meter of the present invention may be provided for at this remote location. FIG. 11 also shows the use of a movable slider 272 so as to selectively contact individual ones of the junctions between the strips of the photosensitive material and the strips of the electroluminescent material. The use of the movable slider 272 provides for an output signal at a predetermined one of the output indications in accordance with the position of the slider.

Since the embodiment of FIG. 11 does not produce a visible output indication from the ends of the individual light transmission means 266, it is not necessary to twist the light transmission means to achieve a vertical output indication perpendicular to the opening 262. Actually, with the embodiment of FIG. 11 and other embodiments, the light transmission means may be moved from the position shown in the drawings to a position intermediate the light source and the cylindrical member. The light transmission means would then be used to produce parallel light from the light source so that the parallel light could be directed through the cylindrical member to produce a sharp output indication to activate the photoconductors.

FIG. 12 illustrates an alternative embodiment to the embodiment shown in FIG. 11. Specifically, in FIG. 12 a housing 300 includes a cylindrical member 302 which cylindrical member may be of the type shown either in FIG. 3a or FIG. 4a. It is to be appreciated that in the various embodiments illustrated in the drawings, light reflected from the cylindrical member as shown in FIG. 8 may be used in place of light passing through the cylindrical member, as shown in FIG. 1. Therefore, the cylindrical member 302 may also be of the type shown in FIG. 9a or 10a ifa reflective light system is used.

The cylindrical member 302 is driven by a drive means 304. Light energy is provide by a light source 301 and reflector 306 which may alternatively be of the type shown in FIG. 11. Light energy in response to the position of the cylindrical member 302 is provided to an opening 308 in a front panel 310, which opening 308 provides for a display area. The output from the display area may be transmitted by a plurality of light pipes 312, which light pipes 312 are essentially similar to the light pipes as shown in FIG. 5. The ends of the light pipes 312 are coated with photosensitive material 314. One side of each area of photosensitive material 314 is coupled to a source of voltage marked as 8+, and the other sides are individually connected to individual strips of electroluminescent material 316. Each of the strips of electroluminescent material also has one side connected to a source of reference potential such as ground.

It is to be appreciated in the embodiment shown in FIG 12 that as the cylindrical member 302 is rotated, various ones of the light pipes 312 receive light energy from the source of the light 306 so as to produce a change in electrical characteristics of individual ones of the strips of the photosensitive material 314. If, for example, the photosensitive material is photoresistive material, the change in the electrical characteristics of the photoresistive material may be such to produce a current flow through the particular one of the electroluminescent strips 316. The flow of current through the electroluminescent material produces an output flow in accordance with this current flow. It is to be appreciated that this output indication may be a sequential movement of the glow with the activation of individual ones of the strips 316 to the exclusion of others, or the output indication may be a progressive illumination of successive ones of the strips 316 so that the glow area extends in length. The type of output indication, of course, would de pend upon the type of cylindrical member used.

A further embodiment of theinvention is shown in FIG. 13 and includes the use of a reflected light system and an output light transmission means of the same type shown in FIG. 8. In FIG. 13 an outer housing 350 encloses a cylindrical member 352. The cylindrical member 352 may be of the type shown in FIG. 9a or the type shown in FIG. 10a and includes reflective and light-absorbing areas. Specifically, the means of directing the light towards the reflective areas of the cylindrical member 352 and the light transmission means is of the same type as shown in FIG. 8 and reference is made to FIG. 8 for a full description.

In FIG. 13 the drive means for the cylindrical member 35 2 is a dArsonval meter movement which is located completely within the cylindrical member 352. Specifically, the drive means includes a pair of permanent magnets 354 and 356. The permanent magnets 354 and 356 have north and south poles, Z

as shown in FIG. 13. A shell ofmagnetic material 358 encloses the permanent magnets 354 and 356 and provides a return flux path for the flux lines. As can be visualized, all of the flux lines extend radially before passing into the magnetic material 358. A loop of wire 362 passes through the center of the pair of magnets 356 and 354, as shown at position 364, and also the loop of wire passes through a slot 366 located between the permanent magnet members 354 and 356 and magnetic material 358. The loop of wire 362 may rotate about the center position 364 so that the portion of the loop of wire which fits in the slot 366 may move in the slot. It is to be appreciated that the loop of wire 362 represents many turns of wire.

The ends ofthe wire 362 support a connecting member 368, which connecting member connects the cylindrical member 352 with the wire. Therefore, as the wire moves in the slot 366 the cylindrical member 352 is rotated about the central position. The input signals to be measured are applied to the loop of wire. The magnetic flux lines entering the shell of magnetic material 358 are always in the same direction in relation to the wire and are always at right angles to the wire in the slot 366. A force is produced to move the loop of wire in the slot in accordance with the magnitude of the signal in the loop of the wire.

The above-described meter movement has advantages over the normal meter movement since it may be mounted completely within the cylindrical member 352 and, in addition, the above-described meter movement provides for a rotation of at least 270. The meter movement shown in FIG. 13 may extend throughout the length of the cylindrical member 352 so as to provide for an increased torque due to the relatively large size of the permanent magnets 354 and 356 and long wire length 362. In addition, a single meter movement may be placed within one end of the cylindrical member, or a pair of meter movements, one within each end of the cylindrical member, may be used.

FIGS. 14a and 14b illustrate additional structures which may be used for the individual light transmission means with the previously illustrated embodiments. In FIG. 14a individual light transmission means 400 includes baffles 402 and has light-absorbing portions 404 and light-reflecting portions 406. The light-reflecting portion 406 may be filled with a clear plastic such as a clear epoxy and has an end surface 408 structured to present an output indication.

The light energy shown by the lines 410 which light energy is produced along the display axis is transmitted by the light transmission means 400 to produce the output indication at the end surface 408. The baffles 402 are twisted at the output end 408 so as to present a vertical output indication, while the input end is parallel to the helix. It is to be appreciated that a plurality of individual light transmission means 400 are located adjacent to each other along the display axis. Adjacent light transmission means 400 may share baffle members 402. The structure of FIG. 14a produces a brighter output indication at the end 408 since the gathered light energy is concentrated at a smaller surface 408 than the incident surface 412.

The structure of FIG. 14b is reversed in operation to that shown in FIG. 14a. FIG. 14a includes individual light transmission means 450 constructed of baffles 452 having light-absorbing surfaces 454 and light-reflecting surfaces 456. Light energy 458 present along the display axis is transmitted and produces an output indication at end surface 460. The output indication, therefore, is relatively large compared to the input area. Both the structures of FIG. 14a and 14b may be twisted at or near the narrow end so as to be easier to construct. In both cases, the light output ends 408 and 460 are vertical and the light incident ends 412 and 462 are parallel to the helix line on the rotating cylinder.

The present invention, therefore, discloses a linear meter which provides for a linear output indication in accordance with a rotation of a cylindrical member. The cylindrical member includes a helical line, which helical line presents a progressive linear movement of portions of the helical line along a display axis which axis is parallel to the central rotational axis of the cylindrical member. Parallax is substantially eliminated and a sharp output indication is produced through the use of a plurality of light transmission means which produce essentially parallel light from an original light source. The light transmission means may be located adjacent to the light source or, in the example given, the light transmission means may be located adjacent to the display area to transmit the light energy from the display area to a second area.

The light transmission means may be a plurality of small light pipes or may be light transmission members which have twisted ends so as to be aligned with the helical line along the cylindrical member. Baffle members may be included within the light transmission members so that unwanted light is not transmitted between the light transmission members. Also, light-absorbing surfaces may be used on the ends of the light transmission members adjacent to the display area so as to eliminate unwanted light.

The invention has also been disclosed with light sources which reflect light energy from the cylindrical member and with light sources which pass the light energy through the cylindrical member. The invention also includes other aspects, such as the use of photosensitive and electroluminescent material to provide for electrical output signals and remote output indications. In addition, a drive system has been described which may be located completely within a cylindrical member, which drive system operates over a large arc and which drive system provides for a large torque. Although the present invention has been described with reference to par ticular embodiments, various adaptations, modifications and combinations may be made. The invention, therefore, is only to be limited by the appended claims.

lclaim:

l. A linear meter, including a cylindrical member including a helical line on the surface of the cylindrical member and with the cylindrical member rotatable about a central axis,

first means operatively coupled to the cylindrical member for producing a rotational movement of the cylindrical member about the central axis and with the helical line on the surface of the cylindrical member presenting a linear display to a display area adjacent to the cylindrical member which display area extends along a display axis parallel to the central axis,

a plurality of individual light transmission means each having first and second ends positioned adjacent to each other and with the first ends positioned adjacent to the display area along the display axis for sequentially transmitting the linear display to the individual light transmission means in accordance with the rotation of the cylindrical member and with the first ends twisted to be aligned with the helical line, and

a plurality of light baffles and with at least one baffle located between each adjacent pair of light transmission means.

2. The linear meter of claim I wherein the light baffles are light-absorbent in the area adjacent to the first ends of the light transmission means and are light-reflective in the area adjacent to the second ends of the light transmission means.

3. The linear meter of claim 1 wherein the second ends of the light transmission means each contain at least one lightdiffusing area so as to produce an output indication of the linear display. 

1. A linear meter, including a cylindrical member including a helical line on the surface of the cylindrical member and with the cylindrical member rotatable about a central axis, first means operatively coupled to the cylindrical member for producing a rotational movement of the cylindrical member about the central axis and with the helical line on the surface of the cylindrical member presenting a linear display to a display area adjacent to the cylindrical member which display area extends along a display axis parallel to the central axis, a plurality of individual light transmission means each having first and second ends positioned adjacent to each other and with the first ends positioned adjacent to the display area along the display axis for sequentially tranSmitting the linear display to the individual light transmission means in accordance with the rotation of the cylindrical member and with the first ends twisted to be aligned with the helical line, and a plurality of light baffles and with at least one baffle located between each adjacent pair of light transmission means.
 2. The linear meter of claim 1 wherein the light baffles are light-absorbent in the area adjacent to the first ends of the light transmission means and are light-reflective in the area adjacent to the second ends of the light transmission means.
 3. The linear meter of claim 1 wherein the second ends of the light transmission means each contain at least one light-diffusing area so as to produce an output indication of the linear display. 